An idea to make it a viable option would be to incorporate the additional pet skill options they have for instance:
Felhunter: additional skill allows it to devour a magic buff on an enemy and recover energy; The GoS update could give us the skill as an addition to the interrupt and have it either recover health or soul shards.
Imp The additional skill allows the imp to flee to the master; we could use this as an oppourtunity to gain a movement skill by allowing us to flee to an ally. (a Warlock lore like option could be Crush a soul shard to channel demonic energy to bring yourself to an allied target losing some health in the process
Void walker additional skills are for tanking which could theoretically open up new design options for warlock and maybe redesign affliction into a cast tank option.
Succubus Additional ability is a speed debuff and additional damage taken buff from the pet, the GoS option could give your targets who are afflicted by curse of exhaustion to take increased damage from you as the debuff expires